INTERACTION OF DNA WITH RIBOSOMES IN CELL-FREE PROTEIN SYNTHETIZING SYSTEMS OF CHLORELLA PYRENOIDOSA

1. In cell-free protein synthetizing systems of the green alga Chlorella pyrenoidosa, DNA from various sources enhances the amino acid incorporation. 2. This stimulation is neither inhibited by actinomycin D nor by chloramphenicol or cycloheximide (actidione). 3. In the presence of ribonuclease, some precipitable polypeptide is formed with DNA, although the endogenous incorporation is completely inhibited by ribonuclease. 4. After sucrose density gradient centrifugation, polysomal aggregates of ribosomes with DNA are found. Electron micrographs of such polysomes show a direct association of the DNA molecule with several ribosomes. 5. In Chlorella, direct translation of DNA can be obtained also in the presence of neomycin. The kinetics of this reaction are different from those of endogenous m-RNA mediated and of DNA stimulated polypeptide synthesis. © 1969, Walter de Gruyter. All rights reserved.